Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pension Benefits [Member]
Components of net periodic cost (benefit) for pension and postretirement plans
Service cost	$ 50	$ 48	$ 99	$ 96
Interest cost	220	234	441	468
Expected return on plan assets	(278)	(253)	(557)	(506)
Amortization of net actuarial loss/prior service cost	194	178	388	356
Net periodic cost recognized	186	207	371	414
Postretirement Benefits [Member]
Components of net periodic cost (benefit) for pension and postretirement plans
Service cost	1	0	1	1
Interest cost	1	1	2	2
Amortization of net actuarial loss/prior service cost	(117)	(118)	(234)	(236)
Net periodic cost recognized	$ (115)	$ (117)	$ (231)	$ (233)